is probably a consequence of the combination of the influence
of the fluorine containing environment and the field assisted flow of
the prior formed barrier oxide layer. The energy dispersive X-ray spectroscopy
(EDS) spectrum of a spot in the anodic oxide layer displaying
the elements present in the film is shown in Fig. 1c. The EDS spectrum
indicates the presence of fluorine in the Barker's reagent-formed oxide
layer, which confirms the ingress of fluoride ions through the film
fromthe electrolyte. In Fig. 1d, an opticalmicrograph showing different